Variable Expansion inside a for loop - batch-file

I understand that this is a common problem but I am unable to decipher the answers and suggestion in other questions to make my specific script work.
#echo on
setlocal EnableDelayedExpansion
set directory=%1
set file_list=%2
for /f "tokens=*" %%i in (%file_list%) DO (
set newName=!%%i:~0,5!
move "%directory%\%%i" "%directory%\!%newName%!s.jpg" )
endlocal
This is giving me this output with echo on
set newName=!image.png:~0,5!
move "\\server\path\to\image.png" "\\server\path\to\!!s.jpg"
So clearly newName is null when I need it, so I can't even begin to troubleshoot the most likely syntax issues when trying to cut it to 5 characters.
THANKS!

set "newName=%%i"
set "newName=!Newname:~0,5!"
You can't substring a metavariable like %%i. You need to assign it to a standard environment variable, then substring using the method indicated (!var...! in delayedexpansion mode because the altered value of the variable is required within a code block)
The quotes simply delimit the strings involved to ensure that any invisible stray spaces on the line are not included.

Related

Extract a GUID from XML in batch script

I have a string
<?define customGUID= "DA7C36F0-A749-4CC5-9575-398C06039325"?>
I am trying to trim out DA7C36F0-A749-4CC5-9575-398C06039325 from this line.
To begin with I tried to set this string in a variable but I am not able to do that may be because of < and ? in string, I tried:
set "var=<?define customGUID= "DA7C36F0-A749-4CC5-9575-398C06039325"?>"
But later I was able to fetch the string somehow at runtime and now I have the variable
line=<?define customGUID= "DA7C36F0-A749-4CC5-9575-398C06039325"?>
I am not able to figure out how can I trim only value i.e DA7C36F0-A749-4CC5-9575-398C06039325 out of this variable using batch script.
I gave it a try to trim suffix at least with:
set "line=%line:"?>%"
But getting error, can anyone help with better approach?
Note: the spaces are included in string
You can split the string using " as a delimiter, but since quotes are used to specify for loop options, the syntax looks a little different than usual:
#echo off
setlocal enabledelayedexpansion
set "line=<?define customGUID= "DA7C36F0-A749-4CC5-9575-398C06039325"?>"
echo !line!
for /f tokens^=2^ delims^=^" %%A in ("!line!") do set "line=%%A"
echo !line!
You may use this very simple trick:
#echo off
setlocal EnableDelayedExpansion
set "var=<?define customGUID= "DA7C36F0-A749-4CC5-9575-398C06039325"?>"
set "i=0" & set "v0=%var:"=" & set /A i+=1 & set "v!i!=%"
echo Desired string: [%v1%]
If you want to know how this works, remove the #echo off line and carefully review what appears in the screen...
Your command line:
set "line=%line:"?>%"
does not make sense, because there is an =-sign missing (refer to sub-string substitution):
set "line=%line:"?>=%"
To trim away the unwanted prefix you could remove everything up to the first quotation mark:
set "line=%line:*"=%"
However, this only works when you do that after having removed the suffix, because you are dealing with unbalanced quotation marks, which are problematic together with immediate variable expansion. If you want to change the order, you have to implement escaping in order not to exhibit the redirection operator > unquoted:
set ^"line=%line:*"=%"
set "line=%line:"?>=%"
To avoid the need of escaping depending on the input string, use delayed variable expansion, like this:
set "line=<?define customGUID= "DA7C36F0-A749-4CC5-9575-398C06039325"?>"
set line
rem // First enable delayed expansion:
setlocal EnableDelayedExpansion
rem // Then apply it by replacing `%` with `!`:
set "line=!line:*"=!"
set "line=!line:"?>=!"
set line
rem // This restores the previous state:
endlocal
rem // At this point changes in the variable are no longer available due to localisation:
set line

Problems with Ampersand

I'm making a batch using the current location to make some changes the problem is that this place may have the & and thus cause errors ... I wonder if there is a way to make a script that checks for the & in the variable and if you add has the ^&.
the way I am using this might be.
Set "Local_Script=%~dp0">nul 2>&1
Echo %Local_Script%> a00_Local.ini
Note: The txt file can only be with the way.
Escaping characters is fine when your code is supplying a string literal. But it is often impractical when dealing with existing strings contained within variables.
There are simpler solutions:
1) delayed expansion:
Note that you must assign batch arguments and/or FOR variables to environment variables prior to enabling delayed expansion. Otherwise values containing ! will be corrupted.
#echo off
set "local_script=%~dp0"
setlocal enableDelayedExpansion
echo !local_script!>a00_local.ini
2) transfer the quoted value to a simple FOR variable, then use the ~ modifier to safely remove the quotes:
#echo off
for %%F in ("%~dp0") do echo %%~F>a00_local.ini
3) transfer the quoted string value to a FOR /F variable, which automatically removes the quotes:
#echo off
for /f "delims=" %%F in ("%~dp0") do eho %%F>a00_local.ini

Dealing with potentially necessary escape characters

Related: Using batch echo with special characters
How do I deal with using escape characters on text that might or mightn't be a special character?
Suppose we have user input:
Set /p var=prompt:
Now, I need to make sure that the text gets interpreted as text even if the user enters something like a special character. But I cannot simply add ^ before the variable...because that'd cancel the variable. The ^^%var% and ^%%var% options don't seem to work either.
How do I go about doing this?
You should realize that the escapes are required in the source code of your program or when you expand a variable via %variable% or in the replaceable parameter of a for command. This is not required if you expand a variable via !delayed! expansion. So, your problem may be easily solved this way:
setlocal EnableDelayedExpansion
Set /p var=prompt:
echo !var!
The standard method to avoid the problem when you read a file that may have special characters is enclosing the value of the replaceable parameter in quotes when the value is asigned with Delayed Expansion disabled, and then Enable Delayed Expansion in order to manage the value. Of course, this method forces to insert an endlocal command inside the loop:
for /F "delims=" %%a in (anyFile.txt) do (
set "line=%%a"
setlocal EnableDelayedExpansion
echo Line with special characters: !line!
endlocal
)
Not possible. The shell processes the user input before your script does. Your script won't even know the user typed an escape character.

How to split string without for loop in batch file

I want to split a string in two parts, without using any for loop.
For example, I have the string in a variable:
str=45:abc
I want to get 45 in a variable and abc in another variable. Is it possible in batch file?
pattern is like somenumber:somestring
You could split the str with different ways.
The for loop, you don't want use it.
The trailing part is easy with the * (match anything until ...)
set "var2=%str:*:=%"
The leading part can be done with a nasty trick
set "var1=%str::="^&REM #%
The caret is needed to escape the ampersand,
so effectivly the colon will be replaced by "&REM #
So in your case you got the line after replacing
set "var1=4567"&REM #abcde
And this is splitted into two commands
set "var1=4567"
REM #abcde`
And the complete code is here:
set "str=4567:abcde"
echo %str%
set "var1=%str::="^&REM #%
set "var2=%str:*:=%"
echo var1=%var1% var2=%var2%
Edit 2: More stable leading part
Thanks Dave for the idea to use a linefeed.
The REM technic isn't very stable against content with quotes and special characters.
But with a linefeed trick there exists a more stable version which also works when the split argument is longer than a single character.
#echo off
setlocal enableDelayedExpansion
set ^"str=456789#$#abc"
for /F "delims=" %%a in (^"!str:#$#^=^
!^") do (
set "lead=%%a"
goto :break
)
:break
echo !lead!
Solution 3: Adpated dbenhams answer
Dbenham uses in his solution a linefeed with a pipe.
This seems a bit over complicated.
As the solution uses the fact, that the parser removes the rest of the line after an unescaped linefeed (when this is found before or in the special character phase).
At first the colon character is replaced to a linefeed with delayed expansion replacement.
That is allowed and the linefeed is now part of the variable.
Then the line set lead=%lead% strips the trailing part.
It's better not to use the extended syntax here, as set "lead=%lead%" would break if a quote is part of the string.
setlocal enableDelayedExpansion
set "str=45:abc"
set ^"lead=!str::=^
!"
set lead=%lead%
echo "!lead!"
You can try this . If its fixed that numbers to left of the colon will be always 2 & to the right will be 3. Then following code should work assuming your str has the value.
set "str=45:abc"
echo %str%
set var1=%str:~0,2%
set var2=%str:~3,3%
echo %var1% %var2%
Keep me posted. :)
It seems pointless to avoid using a FOR loop, but it does make the problem interesting.
As jeb has pointed out, getting the trailing part is easy using !str:*:=!.
The tricky bit is the leading part. Here is an alternative to jeb's solution.
You can insert a linefeed into a variable in place of the : using the following syntax
setlocal enableDelayedExpansion
set "str=45:abc"
echo !str::=^
!
--OUTPUT--
45
abc
The empty line above the last ! is critical.
I'm not sure why, but when the output of the above is piped to a command, only the first line is preserved. So the output can be piped to a FINDSTR that matches any line, and that result directed to a file that can then be read into a variable using SET /P.
The 2nd line must be eliminated prior to using SET /P because SET /P does not recognize <LF> as a line terminator - it only recognizes <CR><LF>.
Here is a complete solution:
#echo off
setlocal enableDelayedExpansion
set "str=45:abc"
echo(!str::=^
!|findstr "^" >test.tmp
<test.tmp set /p "var1="
del test.tmp
set "var2=!str:*:=!"
echo var1=!var1! var2=!var2!
Update
I believe I've mostly figured out why the 2nd line is stripped from the output :)
It has to do with how pipes are handled by Windows cmd.exe with each side being processed by a new CMD.EXE thread. See Why does delayed expansion fail when inside a piped block of code? for a related question with a great answer from jeb.
Just looking at the left side of the piped command, I believe it is parsed (in memory) into a statement that looks like
C:\Windows\system32\cmd.exe /S /D /c" echo {delayedExpansionExpression}"
I use {delayedExpansionExpression} to represent the multi-line search and replace expansion that has not yet occurred.
Next, I think the variable expression is actually expanded and the line is broken in two by the search and replace:
C:\Windows\system32\cmd.exe /S /D /c" echo 43
abc"
Only then is the command executed, and by normal cmd.exe rules, the command ends at the linefeed. The quoted command string is missing the end quote, but the parser doesn't care about that.
The part I am still puzzled by is what happens to the abc"? I would have thought that an attempt would be made to execute it, resulting in an error message like 'abc"' is not recognized as an internal or external command, operable program or batch file. But instead it appears to simply get lost in the ether.
note - jeb's 3rd comment explains why :)
Safe version without FOR
My original solution will not work with a string like this & that:cats & dogs. Here is a variation without FOR that should work with nearly any string, except for string length limits and trailing control chars will be stripped from leading part.
#echo off
setlocal enableDelayedExpansion
set "str=this & that:cats & dogs"
set ^"str2=!str::=^
!^"
cmd /v:on /c echo ^^!str2^^!|findstr /v "$" >test.tmp
<test.tmp set /p "var1="
del test.tmp
set "var2=!str:*:=!"
echo var1=!var1! var2=!var2!
I delay the expansion until the new CMD thread, and I use a quirk of FINDSTR regex that $ only matches lines that end with <cr>. The first line doesn't have it and the second does. The /v option inverts the result.
Yes, I know this is a very old topic, but I just discovered it and I can't resist the temptation of post my solution:
#echo off
setlocal
set "str=45:abc"
set "var1=%str::=" & set "var2=%"
echo var1="%var1%" var2="%var2%"
You may read full details of this method here.
In the Light of people posting all sorts of methots for splitting variables here i might as well post my own method, allowing for not only one but several splits out of a variable, indicated by the same symbol, which is not possible with the REM-Method (which i used for some time, thanks #jeb).
With the method below, the string defined in the second line is split into three parts:
setlocal EnableDelayedExpansion
set fulline=one/two/three or/more
set fulline=%fulline%//
REM above line prevents unexpected results when input string has less than two /
set line2=%fulline:*/=%
set line3=%line2:*/=%
set line1=!fulline:/%line2%=!
set line2=!line2:/%line3%=!
setlocal DisableDelayedExpansion
echo."%line1%"
echo."%line2%"
echo."%line3%"
OUTPUT:
"one"
"two"
"three or/more//"
i recommend using the last so-created partition of the string as a "bin" for the remaining "safety" split-characters.
Here's a solution without nasty tricks for leading piece
REM accepts userID#host
setlocal enableDelayedExpansion
set "str=%1"
set "host=%str:*#=%"
for /F "tokens=1 delims=#" %%F IN ("%str%") do set "user=%%F"
echo user#host = %user%#%host%
endlocal

How can I URL-encode spaces in an NT batch file?

I have the misfortune of working with a program which requires all filenames passed into it to be valid URLs. (No, I don't know why.) Rather than having to drop to the command line and hand-craft file: URLs each time, I'm throwing together a batch file onto which I can simply drop files dragged from the Windows GUI.
A full, proper URL encoder is beyond my needs or interest (most of the characters the app chokes on aren't valid in Windows filenames, anyway), but the two cases I do need to solve are backslashes and spaces. Backslashes are easily handled by variable replacement syntax (SET URL=%URL:\=/%), but spaces are tricky — % is special for both URLs and batch files.
Neither type of batch escaping I'm familiar with (^%, %%) allows the variable replacement to behave as desired and I haven't had any success Googling a solution. Can any batch gurus help me out?
Here's what I have so far:
#ECHO OFF
SETLOCAL
SET URLPATH=file:/%~dp1
SET URLPATH=%URLPATH:\=/%
REM none of these work
REM SET URLPATH=%URLPATH: =%20%
REM SET URLPATH=%URLPATH: =%%20%
REM SET URLPATH=%URLPATH: =^%20%
REM works; I just need to figure out how to generate it
SET URLPATH=file:/C:/Documents%%20and%%20Settings/bblank/example.dat
stupidapp.exe %URLPATH%
ENDLOCAL
Side note - I believe you want %~f1 instead of %~dp1
You need to switch over to delayed expansion.
#echo off
setlocal enableDelayedExpansion
set "URLPATH=file:/%~f1"
set "URLPATH=!URLPATH:\=/!"
set "URLPATH=!URLPATH: =%%20!"
stupidapp.exe !URLPATH!
endlocal
A bit more work is required if any of your file names happen to contain the ! character because it will be corrupted when %1 is expanded if delayed expansion is enabled.
#echo off
setlocal disableDelayedExpansion
set "URLPATH=file:/%~f1"
setlocal enableDelayedExpansion
set "URLPATH=!URLPATH:\=/!"
set "URLPATH=!URLPATH: =%%20!"
stupidapp.exe !URLPATH!
endlocal
endlocal
dbenham's solution is almost certainly preferable (being rather easier to read), but for the sake of completeness, here is an alternative solution:
SET URLPATH=file:/%~dp1
SET URLPATH=%URLPATH:\=/%
REM for each space in the path, split the path into the portions before and after
REM that space, then join them with an escaped space
:ESCAPE_SPACE
SET TRAILING=%URLPATH:* =%
CALL SET URLPATH=%%URLPATH: %TRAILING%=%%
SET URLPATH=%URLPATH%%%20%TRAILING%
IF NOT "%URLPATH%"=="%URLPATH: =%" GOTO ESCAPE_SPACE
stupidapp.exe %URLPATH%

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